Since Web service transactions(WST) in its context may require long periods of time to complete, for the reliability of composite Web services executions, A failed WST will affect the execution process. However, the existing approaches have not considered a weaker notion of atomicity based on compensations. Thus we present a composition compensation mechanism based on paired net to implement partial or full compensation of the committed activities. The introduction of this method can accurately construct services composition based on Paired net and establish agile compensation-triggered mechanism which can satisfy prospective compensation requirements. We discuss the compensation execution semantics of sequence and parallel composition patterns to ensure the weaker notion of atomicity by performing compensation when failure occurs.